Scoundrel shows terrible outrage at being rejected (5)
I believe the answer is:
rogue
'scoundrel' is the definition.
(I know that rogue is a type of scoundrel)
'terrible outrage at being rejected' is the wordplay.
'terrible' indicates an anagram.
'being rejected' is a deletion indicator.
'outrage' with 'at' taken away is 'ourge'.
'ourge' anagrammed gives 'ROGUE'.
'shows' is the link.
(Other definitions for rogue that I've seen before include "Impish, likeable person" , "Profligate" , "A dishonest or unprincipled person" , "Fraud" , "Rascal or reprobate" .)